Moisture requirement calculator



Jan. 1960 c. F. WEISGERBER 2,920,827

MOISTURE REQUIREMENT CALCULATOR Filed June 21, 1954 M LD CGNVEYOR United States Patent MOISTURE REQUIREMENT CALCULATOR Charles F. Weisgerber, Whittier, Calif., assignor of onehalf to Paul R. Francis, Los Angeles, Calif.

Application June 21, 1954, Serial No. 438,083

13 Claims. (Cl. 235-179) This invention relates to a moisture requirement calculator for indicating a resultant or requirement and is more particularly concerned with an electrical device which indicates the amount of moisture required in order to condition materiahsuch as foundry sand or the like, and is preferably an electrical analogue computing apparatus.

In the operation of foundries, molds for metal castings are made from damp sand, which molds are known in the trade as green sand molds. The moisture percentage or content in green sand molds is quite critical in respect to the workability of'the sand and to the eifect on the finished mold when molten metal is introduced into the mold. Sanddeficient in moisture may have poor strength while green and cause washing and cutting of the mold surfaces when molten metal is poured into the mold resulting in defective castings.

Heretofore, it has been common practice to make frequent moisture determinations and to use the best judgment of an experienced and competent sand mill operator in order to control the moisture content. The moisture content must be kept within a close range and there are a number of variables that operate to upset the moisture content to the end that it has been found to be humanly impossible for the mill operator preparing the sand to consistently evaluate the several variables in their proper proportions. Some of the variables that may be evaluated are weight of sand milled, milling time, sand temperature, relative humidity, volume of air drawn through the sand mill, air temperature and movement of air over conveyor belts, etc. It will be understood that some of these variables are rather insignificant while others have a profound influence on the moisture content of the material or sand involved.

It is an object of this invention to provide an apparatus that is responsive to condition surrounding an operation of the character referred to which determines unknown requirements so that it is accurately determined what that requirement is. In the particular case under consideration the requirement is the amount of moisture to be added to the sand in order to deliver the sand to a given point with a consistent moisture content.

. 2 accurately determined and the required amount of moisture to be added-to the mixing operation involved in connection with preparing the sand is immediately indicated.

The various objects and features of my invention will be fully understood from the following detailed description of typical preferred forms and applications of my invention, throughout which description reference is made to the accompanying drawings, in which:

Fig. 1 is a diagrammatic view of the apparatus of the present invention applied to a foundry operation. Fig. 2 graphically illustrates the principle of the present invention as applied to a scale or balance. Fig. 3 is an electrical diagram showing the basic circuit involved in the present invention, and Fig. 4 is an electrical diagram illustrating a more complex form of the electrical apparatus of the present invention.

The apparatus is illustrated graphically in Fig. 2 of the drawings in the form of a multibeam balance. To the left of the fulcrum are several suitable graduated beams each representing one of the variables with which the invention is concerned. It will be observed that the zero points do not all occur at the same end of the beams and that the sizes of the several poises or weights, vary. This dilference in size. represents the relative value or weighting of the several factors as their effect is influenced by the operating conditions.

' until the beams are in balance.

It is a feature of this invention that the sum of all the weights to the left of the fulcrum when they are in their most distant position, is equal to the weight on the right when it is in itsmost distant position from the fulcrum- After adjusting the several poises on the left hand side in accordance with data made available from appropriate instrument readings the poise on the right is adjusted The graduated scale on the right hand side then indicates the water requirement that must be added to the milling operation.

This balanced beam computer though workable would not be practical in foundry operations, particularly if handled by an average sand mill operator. Therefore, I have by the present invention provided a means in the form of an electrical apparatus which correlates all of the various conditions involved and gives to the mill operator a resultant amount of moisture or water to be added to-or omitted from the milling operation.

The apparatus of'the present invention for indicating a requirement based upon surrounding conditions is an electrical apparatus and may be considered as an 7 analogue computer, and involves essentially a power supply A,'a plurality of condition sensing elements B, a current detecting means C and a requirement indicating scale D. The apparatus further involves a balancing means E for the sensing elements, one or more circuit It is another object of this invention to provide an electrical apparatus for indicating a resultant or unknown requirement which apparatus is responsive to a plurality of variable conditions. The particular electrical apparatus that I have illustrated indicates the moisture requirement of the material involved by showing the amount of moisture required in order to bring the material to a desired condition.

It is still another object of this invention to provide a simple and inexpensive apparatus of the character referred to which is responsive to dilferent variables such as material temperature, material moisture content, air temperature and humidity, etc., to the end that opinion and guess Work is completely eliminated. With the particular form of the invention that I have provided the moisture requirement of the material or molding sand is adjusting means F and a circuit balancing means G. The power supply that I have provided may be any suitable source of electrical energy and is under control of a switch 10. The power supply circuit is carried by upper and lower buses 11 and 12, as shown in the diagrams. The buses 11 and 12 are of opposite polarity, as illustrated, and may be considered as being of opposite polarity even when employing alternating current.

The present invention is concerned primarily with the factors surrounding a foundry operation involving the various conditions of the material and other elements involved in the operation. For example, air temperature, said temperature, time required to mix the sand, time required to convey or transport the sand, time required to handle the sand in making molds and the quality or type of sand involved, etc. I have, therefore, provided a plurality of condition sensing elements B, one element for each of the conditions to be evaluated by the apparatus. It is to be understood, however, that the present invention is applicable to other operations such as application to a vehicle, for example an aircraft, where the invention can be employed to respond to known quantities.

For those conditions such' as varying temperature conditions, I have provided elements B in the form. of temperaturei robes 13, 1'4, 1'5 andt1'6, while for these conditions which are more or less constant I' have provided manually controllable elements B in the formof adjustable impedance elements or rheostats, 17, 1'8, 19 and 20.

The four probes are wire wound temperature sensitive resistance elements and are used to measure the four varying temperatures involved. The particular amount of resistance in any one of the elements-B is governed by the value, weighting or the amount" of" efiect which the particular condition has upon the material'. or sand; That is, when a particular. condition has littleefiectthechange in the impedance of the elements Bis low, whereas when a particular condition has great" effect the change in the impedance of the elements is highl Tlie' elenientslB are so designed that the conditionshavingthe mosteftect;

will affect the electrical circuit involve d in'the apparatus a greater amount for a givenvolt'age carried by the buses 11 and 12. 7 t

The sensing elements B" are either'related to or connected to the bus 11 or the bus 1'2 dependingupon what efiect the particular condition involved has upon the material and also upon whether the sensing elementhas a positive or negative coefficient with respect to the condition measured. That is, if the condition associated with a sensing element has a positive efiect upon the material, that element may be connected'to the bus 11, whereas if the condition has a negative effect that ele ment may be connected to the bus 12.

Further, those sensing elements B related to conditions which have equal effect upon the material or sand are arranged'in series across the buses 11 and-12; For the purpose of illustration, a typical situation is shown in Fig. 3 of the drawings where the conditions associated with the probes 13 and 14; respectively, have an opposite effect upon the material or sand and also have anequal elfect at a given-temperature. The same relationship of conditions applies to the probes 15 and 16. For example, the probe 13 is associated with air temperature, while the probe 14' is associated with sand" temperature, and the probe 15 is associated with'wet bulb temperature of air while the probe 16 is associated with air temperature. his to be understood that the elements forming a sensing element 8 may be composed'o fseveral impedances in parallel or in series; and the" sensing elements B may be arranged in various; manners, that is, they may be arranged to give the sum ofdifferent conditions, or to give the relationship between different conditions:

It is-' to be understood that'each sensing element B' is carried in a circuit'made up of' two lines so that elements B may be remotely positioned ascircumstances require and a third equalizing line may be added to compensate for line variations. As shown in Fig. 4 of the drawings the probe 13'is carried by a pair of lines 21 and 22, the prohe 14 is carried by a' pair of lines 23 and 24, the probe 15'1scarried by a pair of lines 25 and 26, the'probe 16 is carried by a pair of lines 27 and 28, the rheostat 17 is carried by a pair of lines 29' and 30, the rheostat 18 is carried by a pair of lines 31 and 32, the rheostat 19 is carried by a pair of lines 33 and 34, and the rheostat 20 is carried by a pair of lines 35 and 36-. As shown in Fig. 4 of the drawings, the sensing elements B which are associated in series between the lines 11 and 12, are electrically connected by joining the lines 22"and 2-4a't'37, by oining-thelines 26 and 28 at-38; by joining the lines 30 and 32* at 39, andby-joinin g the lines 34-and 36 at 40. Further,= itis recognized that suitable equalizing circuits may beemp'loyed'tocompensate'for variance in current carried'in theselines, inconnec'tion with any one'ofthe probes B, as circumstances require.

Referring particularly to Fig. 3 of the drawings thecurrent detectingmeans C is included in'the'circuitof theapparatus that I Have provided in orderto' indicate the condition of the circuit made up of the sensing elements B as they are efiected by the temperature conditions. In the simple form of the invention illustrated a line 41 joins the electrical connection 37 and 38 and a lead 43 extends from the line 41 to the means C. The means C may be any suitable device or instrument, for example, it may be a galvanometer or the like, and is preferably a null sensing device. The other lead 44 from the means C cooperates with the circuit balancing means hereinafter described. With the circuit in operation as shown in Fig. 3, the galvanometer or means C will'indicate the resultant of the plurality of probes13, 14, 15 and 16.

In Fig. 4 of the drawings the circuit involves both the probes 13, 14, 15 and'16-and theimpedances or rheostats 17, 18, 19 and 20, in which case a line 42 joins the electrical connections 39 and 40 and a jumper 45 electrically joins the lines 41 and 42 to the lead 43. With this circuit inoperation the galvanometer or means C will indicate the resultant of the plurality of bridges or probes and also'therheostats 17, 18, 19 and 20.

The. requirement indicating scale D is an elongate member preferably a straight member, and is characterized by a series of suitably spaced graduations or marks 50 for indicating the quantity of moisture or water to be addedto or omitted from the material or sand. The distance between the marks 50 will be governed by the designand balance of the over-all circuit.

The balancing means E for the sensing elements B is provided to adjust the weight or effect between the sensing elements. For example, I have illustrated impedances in the form of a variable resistor51 at 39 between the lines 30 and 32, and a variable resistor 52 at 40 between the lines 34 and 36. It will be readily seen how the effect of the bridge elements or sensing elements can be adjusted to account for variables that enter into the operation under consideration.

The circuit adjusting means'F is provided in order to adjust the effect of the circuit thus far described with respect to the means C. In practice, there may be several circuit adjusting means F as illustrated in Fig. 4 of the drawings. As shown in Fig. 3 of the drawings, there is only one means F audit is animpedance in the form of a variable resistor 53 in the line 41 between the connections 37 and 38'and between the line'4-1 and the lead 43. The resistor 53 is so related to the line 41 and to the lead 43 that the circuit can be adjusted as to the effect of" the probes that feed into the connection 37 and the probes'that'feed' into the connection 38; When the resistor. 53'is'in a'ncrrnal or'neutral position the circuit istheoretically balanced and when'itis desired to correct or check the balance of the circuit the sensing elements B may be artificially, subjected to identical temperatures, whereupon theresistor 53' can be manually operated to compensate'for any errors:

As shown in Fig. 4 a circuit adjusting means F is also providedbetween the'connections 39 and 40 which operates in' the manner above described, and a means F is alsoprovided in the jumper 45 between the jumper and the lead 43. In this case-the resistor 53 is used to adjust the circuit as between the two groups of sensing elements'B; That is, between the probes and rheostats abovedescribed.

The circuit balancing means G is provided to supply the meansC with a current applied through the lead 44 that is substantially equal tothe result of the current passed'b y the elements B through the lead43. In accordance with the invention the means C is constructed so that it registers positive as well as negative currents and, therefore, has a zero or null position readable on aldial; orthe like. The elements 3 and'their associated circuits are the equivalent of the elements shown in theleft-hand portion of the illustration in Fig. 2 of the drawings asabove described, while the circuit balancing means G is the equivalent of the elements shown in the night-hand portion of the illustration in Fig. 2 of the drawings as above described. The analogy between Fig. 2 of the drawings and the electrical apparatus that I have provided will be readily apparent since it is desired to create a balanced condition between the two sides of the electrical circuit involved in the apparatus.

The means G is an impedance element and is shown as a simple variable resistance element 54, and as illustrated is preferably an elongate straight element. In practice, the resistance 54 has a pointer 55 that cooperates with the scale D hereinabove described.

From the foregoing it will be apparent how the circuit balancing means G can be manually operated to position the pointer 55 thereby adjusting the variable resistance 54 in order to balance the two sides of the electrical circuit involved which will be indicated by a zero reading on the dial of the means C. When the circuit is balanced as indicated by a zero reading on the instrument of means C, it is merely'necessary to read the position of the pointer 55 on the suitably graduated scale D which will indicate the quantity of moisture or water which is required to be added or omitted from w the material or sand.

Having described only typical preferred forms and applications of my invention, I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art and fall within the scope of the following claims.

Having described my invention, I claim:

1. An electrical calculating apparatus for determining the value of a requirement in producing a mixture of material, inclluding, a power supply having upper and lower buses, two pairs of sensing resistance elements in series between the buses and each responsive to a condition affecting the requirement of the mixture, a manually operable balancing means connected between the buses and adapted to equal the current passed by the sensing elements, a manually operable circuit adjusting means in a lead connected to points between the sensing elements of each series of said elements, a null sensing current detecting means having a lead connected to said adjusting means, and having a lead connected to the balancing means, and a scale related to the balancing means and indicating a resultant requirement when the apparatus is balanced by said balancing means.

2. An electrical calculating apparatus for determining the value of a requirement in producing a mixture of material, including, a power supply having upper and lower buses, two pairs of sensing resistance elements in series between the buses and each responsive to a condition affecting the requirement of the mixture, manually operable variable impedances between the sensing elements of each series, a manually operable balancing means connected between the buses and adapted to equal the current passed by the sensing elements, a lead connected between the impedances, a null sensing current 6 pedances, a null sensing current detecting means having a lead connected to the first mentioned lead between the impedances, and having a lead connected to the balancing means, and a scale related to the balancing means and indicating a resultant requirement when the apparatus is balanced by said balancing means.

4. An electrical calculating apparatus for determining the value of a requirement in producing a mixture of material, including, a power supply having upper and lower buses, two groups of sensing resistance elements and each responsive to a condition affecting the requirement of the mixture, each group including two pairs of condition sensing elements in series between the buses, a jumper extending between the two groups of elements, a manually operable balancing means connected between the buses and adapted to equal the current passed by the sensing elements, a null sensing current detecting means having a lead connected to the jumper, and having a lead connected to the balancing means, and a scale related to the balancing means and indicating a resultant requirement when the apparatus is balanced by said balancing means.

5. An electrical calculating apparatus for determining the value of a requirement in producing a mixture of ma terial, including, a power supply having upper and lower buses, two groups of sensing resistance elements and each responsive to a condition affecting the requirement of the mixture, each group including two pairs of condition sensing elements in series between the buses, a manually operable circuit adjusting means in a lead between the sensing elements of each series of elements of one group, a lead between the sensing elements of each series of elements of the other group, a jumper extending between the two groups of elements, a manually operable balancing means connected between the power buses and adapted to equal the current passed by the sensing elements, a null sensing current detecting means having a lead connected to the jumper and a lead connected to the balancing means and indicating a resultant requirement when the apparatus is balanced by said balancing means.

6. An electrical calculating apparatus for determining the value of a requirement in producing a mixture of material, including, a power supply having upper and lower buses, two groups of sensing resistance elements and each responsive to a condition affecting the requirement of the mixture, each group including two pairs of condition sensing elements in series between the buses, manually operable circuit adjusting means in leads between the sensing elements of each series of elements of each group, a jumper extending between the two groups of elements, a

manually operable balancing means connected between connected to the balancing means, and a scale related to detecting meanshaving a lead connected to the first men tioned lead between the impedances, and having a lead connected to the balancing means, and a scale related to the balancing means and indicating a resultant requirement when the apparatus is balanced by said balancing means.

3. An electrical calculating apparatus for determining the value of a requirement in producing a mixture of material, including, a power supply having upper and lower buses, two pairs of sensing resistance elements in series between the buses and each responsive to a condition aifecting the requirement of the mixture, manually operable variable impedances between the sensing elements of each series, a manually operable balancing means connected between the buses and adapted to equal the current passed by the sensing elements, a manually operable circuit adjusting means in a lead connected between the imthe balancing means and indicating a resultant requirement when the apparatus is balanced by said balancing means. 1

7. An electrical calculating apparatus for determining the. value of a requirement in producing a mixture of material, including, a power supply having upper and lower buses, two groups of sensing resistance elements and each responsive to a condition afiecting the requirement of the mixture, each group including two pairs of condition sensing elements in series between the buses, a manually operable circuit adjusting means in a lead between the sensing elements of each series of elements of one group, a lead I between the sensing elements of each series of elements to the balancing means, and a scale related to the ba1anc-- ing means and indicating a resultant requirement when the apparatus is balanced by said balancing means.

8. Anelectrical calculating apparatus for determining the value of a requirement in producing a mixture of material, including, a power supply having upper and lower buses, two groups of sensing resistance elements and each responsive to a condition affecting the requirement of the mixture, each group including two pairs of condition sensing elements in series between the buses, manually operable circuit adjusting means in leads between the sensing elements of each series of elements .of each group, a manually operable circuit adjusting means in a jumper extending between the two groups of elements, a manually operable balancing means connected between the powerbuses and adapted to equal the current passed by the sensing elements, a null sensing current detecting means having a lead connected ,to the circuit adjusting means in the jumper and a lead connected to the balancing means, and a scale related to the balancing means and indicating a resultant requirement when the apparatus is balanced by said balancing means. w

9. An electrical calculating apparatus for determining the value of a requirement in producing a mixture of material, including, a power supply having upper and lower buses, two' groups of sensing resistance elements and each responsive to a condition affecting the requirement of the mixture, each group including two pairs of condition sensing elements in series between the buses, manually variable impedances between the sensing elements of each series, a jumper extending between the two groups of elements, a manually operable balancing means connected between the buses and adapted to equal the current passed by the sensing elements, a null sensing current detecting means having a lead connected to the jumper, and having a lead connected to the balancing means, and a scale related to the balancing means and indicating a resultant requirement when the apparatus is balanced by said balancing means.

10. An electrical calculating apparatus for determining the value of a requirement in producing a mixture of material, including a power supply having upper and lower buses, two groups of sensing resistance elements and each responsive to a condition affecting the requirement of the mixture, each group including two pairs of condition sensing elements in series between the buses, manually variable impedance between the sensing elements of each series, a manually operable circuit adjusting means in a lead between the sensing elements of each series of elements of one group, a lead between the sensing elements of each series of elements of the other group, a jumper extending between the two groups of elements, a manually operable balancing means connected between the powerbuses and adapted to equal the current passed by the sensing elements, a null sensing current detecting instrument having a lead connected to the jumper and a lead connected to the balancing means, and a scale related to the balancing means and indicating a resultant requirement when the apparatus is balanced by said balancing means.

11. An electrical calculating apparatus for determining the Value of a requirement in producing a mixture of material, including, a power supply having upper and lower buses, two groups of sensing resistance elements and each responsive to a condition aifecting the requirement of the mixture, each group including two pairs of condition sensing elements in series between the buses, manually variable impedances between the sensing elements of each series, manually operable circuit adjusting means in leads between the sensing elements of each series of elements of each group, a jumper extending between the two groups of elements, a manually operable balancing means connected between the power buses and adapted to equal the current passed by the sensing elements, a null sensing current detecting means having a lead connected to the jumper and a lead connected to the balancing means, and a scale related to the balancing means and indicating a resultant requirement when the apparatus is balanced by said balancing means.

12. An electrical calculating apparatus for determininglthe value of a requirement in producing a mixture of material, including, a power supply having upper and lower buses, two groups of sensing resistance elements and each responsive to a condition afiecting the requirement of the mixture, each group including two pairs of condition sensing elements in series between the buses, manually variable impedances between the sensing elements of each series, a manually operable circuit adjusting means in a lead between the sensing elements of each series of elements of one group, a lead between the sensing elements of each series of elements of the other group, a manually operable circuit adjusting means in the jumper extending between the two groups of elements, a manually operable balancing means connected between the power buses and adapted to equal the current passed by the sensing elements, a null sensing current detecting means having a lead connected to the circuit adjusting means in the jumper and a lead connected to the balancing means, and a scale related to the balancing means and indicating a resultant requirement when the apparatus is balanced by said balancing means.

13'. An electrical calculating apparatus for determining the value of a requirement in producing a mixture of material, including, a power supply having upper and lower buses, two groups of sensing resistance elements and each responsive to a condition affecting the requirement of the mixture, each group including two pairs of condition sensing elements in series between the buses, manually variable impedances between the sensing elements of each series, manually operable circuit adjusting means in leads between the sensing elements of each series of elements of each group, a manually operable circuit adjusting means in the jumper extending between the two groups of elements, a manually operable balancing means connected between the power buses and adapted to equal the current passed by the sensing elements, a null sensing current detecting means having a lead connected to the circuit adjusting means in the jumper and a lead connected to the balancing means, and a scale related to the balancing means and indicating a resultant requirement when the apparatus is balanced by said balancing means.

References Cited in the file of this patent UNITED STATES PATENTS 1,238,468 Wilsey Aug. 28, 1917 1,758,494 Behr May 13, 1930 2,040,086 ,Goodwillie May 12, 1936 2,637,495 Bubb May 5, 1953 2,815,480 Ruge Dec. 3, 1957 2,846,645 Ruge Aug. 5, 1958 2,848,008 Dietart et ,al. Aug. 19, 1958 OTHER REFERENCES Ergens: Bridge Type Electrical Computers, Review of Scientific Instruments, vol. 18, No. 8, August 1947, pp. 8644567. 

